The Kubina U.S. Pat. No. 4,114,140 is directed to a system for checking the validity of a credit document quickly and easily at the location where the document itself is used and which further requires a minimum memory capacity in order to effect the necessary document check. The system of the Kubina patent is used with an automated product dispensing system for dispensing products such as fuel for large fleet users or for private owners. Such systems are also used for effecting banking transactions during hours when banks normally are closed and for other types of credit card operated systems. Generally in such systems, a card reader control panel or control station is employed; and the transaction is initiated by an insertion of an identified credit card into a card reader by the customer or user of the system. Such cards are uniquely encoded with indicia particularly identifying the customer or user and, in many cases, include other indicia to limit the type and quantity of product which may be purchased or with drawn from the system in response to the use of the card.
In the system disclosed in the Kubina patent, at least some of the data on the card used used with the system is employed for verification of the validity for use of that card to conduct the desired transaction. In the Kubina system, such verification is done locally at the user terminal. Each card is uniquely identified with a verification binary word (typically a four-bit word) which identifies the card. This word then is compared against the same word stored in a memory where it is then identified as being either "valid" or "non-valid" for conducting the transaction. Often it is necessary for the status of a card used with a system to be changed from a "valid" to a "non-valid" status for various reasons. If a credit card is stolen, the identity of that card must be changed in the verification logic of the system to a "non-valid" status; so that it cannot be used to carry out transactions with the system. Other situations arise such as where a customer falls behind in payments, so that it becomes necessary to prevent that customer from using the system until his account is satisfactorily brought up to date.
The Kubina patent discloses a system for permitting the verification logic to be changed to indicate the "non-valid" status of specific cards or customers used with the system whenever desired. In the Kubina system, however, the status change is effected by manually setting switches associated with the verification memory at the fuel dispensing site or utilization site where the memory is located. If there are a large number of potential sites at which the card which is to be "locked out" may be used, it is necessary to manually effect the verification lockout setting with the memory at each one of these different sites or locations. If changes in the status of cards used with the system occur infrequently, such an "on site" manual setting of the verification logic is not particularly inconvenient.
If the locations are widely dispersed, however, or if frequent changes in the validity status of cards used with a system become necessary, it is desirable to effect a change in the verification lockout memory from a central location. Ideally, such a change in the lockout memory file should be effected automatically on command from a central remote location as frequently as becomes necessary during the use of the system. This is particularly desirable in conjunction with fuel dispensing systems where the fuel dispensing locations are scattered over a large area and which may involve thousands of individual cards and/or customers using the system at any given time.